Synthesis of diglycidyl esters of hydroxybenzoic acids and GPC study of molecular heterogeneity

Synthesis of diglycidyl esters of hydroxybenzoic acids

3031

5. G. I. GUREVICH, T r u d y geofizicheskogo i n s t i t u t a A N SSSR, Izd-vo A N SSSR, No. 21, 1953 6. Yu. V. ZELENEV and A. G. NOVIKOV, Zavodsk. lab. 32: 693, 1966 7. Yu. V. ZELENEV a n d A. G. NOVIKOV, Zavodsk. lab. 36: 235, 1970 8. Yu. V. ZELENEV a n d A. G. NOVIKOV, Zavodsk. lab. 44: 888, 1978 9. V. A. KAY(]IN a n d T. I. SOGOLOVA, Zh. fiz. khimii 27: 1039, 1208, 1213, 1325, 1953 10. V. A. KARGIN, T. I. SOGOLOVA and V. M. RUBSHTEIN, Vysokomol. soyed A10: 2017, 1968 (Translated in Polymer Sei. U.S.S.R. 10: 9, 2343, 1968) 11. I. SAKURADA, T. ITO and K. NAKAMAYE, K h i m i y a i tektmologiya polimerov, No. 10, 19, 1964 12. A. R. RZHANITSYN, Nekotoryye voprosy mokhaniki sistem deformiruyushchikhsya vo vremeni (Some Mechanical Problems of Systems Subjected to Deformation over a Period of Time). Stroiizdat, 1949 13. M. A. KOLTUNOV and V. N. BEZUKHOV, Vestnik I~[GU, ser. m a t e m a t i k a i mekhanika, No. 6, 1963 14. M. A. KOLTUNOV, Mekbanika polimerov, 483, 1966 15. M. A. KOLTUNOV, Polzuchest' i relaksatsiya (Creep aud Relaxation). Izd. "Vysshaya shkola", 1976

Polymer Science U.S.S.R. Vol. 22, No. 12, pp. 3081--3036,1980 Printed in Poland

0032-3950180/123031-06507.50/0 © 1981 Pergamon Press Ltd.

SYNTHESIS OF DIGLYCIDYL ESTERS OF HYDROXYBENZOIC ACIDS AND GPC STUDY OF MOLECULAR HETEROGENEITY* A. I . KUZAYEV, N. P. ZAITSEVA, YU. M. KOBEL'CHUK

and N. K. MOSHC1YINSKAYA Branch of the I n s t i t u t e of Chemical Physics, U.S.S.R. Academy of Sciences Dnepropetrovsk Chemico-Technological Institute

(Received l l October 1979) Polyglycidyl esters of m- and p-hydroxybenzoic acids were synthesized b y the interaction of hydroxybenzoie acids with epichlorohydrin and subsequent dehydrochlorination. Gel-permeation chromatography was used to investigate the molecular heterogeneity of the oligomers obtained. I n spite of a variation in conditions of synthesis within a fairly wide range, the esters synthesized are not individual compounds, b u t are oligomers (resins) with a content of the main fraction ranging from 65 to 78w~. %. A d e s c r i p t i o n is g i v e n i n t h e l i t e r a t u r e o f d i g l y c i d y l e s t e r s o f p - h y d r o x y b e a z o i c a c i d [1, 2] a i l d p r o p e r t i e s o f s o l i d i f i e d c o m p o s i t i o n s b a s e d o n t h e m [2]. H o w e v e r , according to results in the literature, these esters have a comparatively low * Vysokomol. soyed. A22: No. 12, 2763-2767, 1980.

A. I. KuzAY~V e$ al.

3032

c o n t e n t of e p o x y g r o u p s r a n g i n g f r o m 21 to 27 wt. % i n s t e a d o f 34-4 wt. ~ , which indicates a p o l y m e r i c chemical s t r u c t u r e . I t w a s i n t e r e s t i n g t o o b t a i n diglycidyl esters w i t h a higher e p o x y g r o u p c o n t e n t a n d e x a m i n e m o l e c u l a r h e t e r o g e n e i t y according to m o l e c u l a r weights a n d f u n c t i o n a l e p o x y g r o u p content. T h i s s t u d y is concerned w i t h t h e s y n t h e s i s of m- a n d p - d i g l y c i d y l esters of h y d r o benzoic acids ( D G E - I a n d D G E - I I , respectively) a n d a g e l - c h r o m a t o g r a p h i c s t u d y o f M W D a n d d i s t r i b u t i o n a c c o r d i n g to t y p e s of f u n c t i o n a l i t y [3]. DGE was synthesized by the interaction of hydroxybenzoic acids with a 15-20-fold amount of epichlorohydrin (ECH) in the presence of triethylbenzylammonimn chloride taken in a proportion of 0.1-1 wt. % of hydroxy acid at ECH boiling point for 1 hour. Dehydrochlorination was carried out at 40-50 ° with sodium or potassium hydroxide taken in a quantity of 1.1 mole per 1 g-equiv, hydroxyl groups. Details of variation of conditions of synthesis were described with subsequent discussion of results. Individual diglycidyl esters were separated from the products by vacuum distillation at 195°]120 dyne/cm 2 in the case of DGE-II and 180°/94 dyne/cm ~ in the case of DGE-I. Chromatographic investigation was carried out using a Waters chromatograph with three styrogel columns of porosity 200, 500 and 1000 fl_ (eluent THF, feed rate 1 ml/min, temperature 25°). A 0.1-0.2 % solution was introduced in 1 rain for analytical fractionation and for preparative fractionation, as a 1% solution in 2 rain. The volume of fractions to be analysed was 5 ml. Fractions were repeatedly introduced into the chromatograph without distillation of THF. F i g u r e 1 shows t y p i c a l c h r o m a t o g r a p h i c curves of resins b a s e d on t h e h y d r o x y benzoic acids, diglycidyl esters of m- a n d p - h y d r o x y b e n z o i c acids. I t can b e seen t h a t D G E - I I is a n i n d i v i d u a l s u b s t a n c e a n d is free f r o m i m p u r i t i e s , while

zll

a

HI

b

J,i, ii ^;',

Ill'/Y,,

j,,

2#

\\

,,.,.

20

jJ'

16 24 Ve , coun,~

20

Fro. 1. Chromatographic cu~ces of resins (a) and DGE (b) based on p- (1) and m-hydroxybe~oie acid (2). Sensitivity 4X (for peaks of D G E - - 2 X ) ; 1 count is 5ml.

Synthesis of diglycidyl esters of hydroxybenzoic acids

3033

D G E - I contains an impurity with a retention volume of 21.6 counts. This impurity was present even in the resins analysed. Preparative fractionation enabled it to be identified as the monoglycidyl ester (MGE). Furthermore, retention volumes were determined for di-, tri, tetramer D G E and associated monoglycidyl esters. Relations between retention volumes and logarithmic molecular weights are shown in Fig. 2. A slight difference can be seen in molecular dimensions, IoyM 3.2H ,nm 2.50 2.8 150

2.4

/ '

15

r

'

ZO

Ve , count

FIG. 2

50 I

2q

0.5 l.O /.5 DGE s~mple , m q Fro. 3

Fie. 2. Relations between retention volumes and log M for DGE-I (1), DGE-II (2), MGE-I (3) and MGE-II (4). Fie. 3. Relation between the height of the chromatographic peak and the DGE sample introduced. according to the position ef substitution (meta- or para-) which decreases with an increase in molecular weight. With an increase in molecular weight the difference in retention volumes of mono- and diglycidyl esters decreases. As a consequence of an open end fragment monoglycidyl ester molecules are somewhat larger than diepoxide molecules. The difference in dimensions is intensified as a result of the solvation of hydroxyl groups b y T H F , therefore, monoglycidyl esters of similar or identical molecular weights are eluted from the column much sooner. This mechanism was observed when studying the fractional composition and MWD of epoxydiane resins [4]. Calibration dependences derived enabled us to calculate b y well-known methods [5] MWD parameters and distribution according to types of functionality of synthetic resins and establish fractional composition. Results are shown in Table 1. A comparison of results of fractional composition, determined analytically and b y preparative fractionation of sample 5 (Table 2) is evidence of the complete identity of results and the accuracy of methods used.

3034

A.I.

KuzA~n~v e$ a/.

Since a correction was introduced in the calculations for the variation of refractive index, according to molecular weight (which in refractometric detection m a y lower the proportion of low molecular weight components of the TA~T.~ 1. P ~ R s

oF ~ o ~ e v ~ a ~ R o a E ~ r ~ w r o~ ~roxY ~ s ~ s ~AS~.D O~¢DGE

Sample*, Epoxy number, % No. 34"4 30"2 29"3 33"1 28'8 26'8

let 250 270 298 250 300 295

250 262 275 250 275 275

1 "00 1.03 1.08 1.00

1.09 1.07

1.93 1"87

2"00 1'92 1"95 1"95 1"95

1.65

1"87

2"00 1 "84 1"87

L

fJA

2.00

1.00

1.86

1"04 1.02 1.02 1"02 1.06

1.91 1.92 1.91 1.77

* Samples1-3 basedon DGE-IIand 4-6,basedon DGE-I. t Calculatedfromthe formulase=Mn"epoxynumber/4300. mixture), it was advisable to evaluate this effect by determining the proportion of DGE, the content of which in the resins studied (Table 2) varied between 60 and 80%. Using D G E - I I a calibration dependence was obtained by an independent method between the height of the chromatographic peak and the amount of substance introduced (Fig. 3) determined from the formula

where G is the sample, rag, v is the rate of elution, ml/min; c--concentration, mg/ml and ~--time of introducing the sample, rain. From the calibration obtained weight fractions of DGE-II were calculated in the resins analysed and results shown in Table 2. A comparison of fractions of DGE obtained by two methods indicates t h a t the variation is within the range of accuracy of the chromatographic experiment and the variation of refractive index has no effect on the results. I t is known [6] t h a t to obtain epoxy compounds with a high epoxy group content based on carboxylic acids, dehydroehlorination of chlorohydrin acid esters should be carried out under mild conditions (at low temperature and in anhydrous medium), in order to prevent hydrolysis of ester groups. Thus, epoxy resin obtained by condensation of p-hydroxybenzoic acid with ECH, followed by dehydrochlorination with solid sodium hydroxide and intermittent distillation of the ECH-water azeotropie mixture at a temperature not higher t h a n TO° (sample 2, Tables 1 and 2), contains the highest proportion of epoxy groups, and has narrow MWD with a ~ 1% content of trimer macromolecules. However, the number-average functionality of the product is not high enough (1.84), which is due to the high content of monoglycidyl ester in the resin as a consequence of incomplete dehydrochlorination. This is confirmed by chemical

Synthesis of diglycidyl e s t e r s

of hydroxybenzoic

303~

acids

a n a l y t i c a l d a t a concerning t h e r e l a t i v e l y high c o n t e n t (up to 1 . 5 ~ ) of organic chlorine in this resin. • T h e use as d e h y d r o c h l o r i n a t i n g a g e n t of solid potassium h y d r o x i d e (sample 5) of high a c t i v i t y a n d more satisfactory solubility in t h e r e a c t i o n m e d i u m , results in a r e d u c t i o n in t h e a m o u n t o f monoglycidyl ester and an increase in t h e v a l u e of fn, b u t the c o n t e n t of high molecular weight fractions in resin il~creases. TABLE

2. FRACTIONAL

Compound

DGE DGE* MGE DGE Dimer MGE Dimer DGE Trimer MGE Trimer DGE Tetramer MGE Tetramer I)GE Pentamer MGE Pentamer Hexamers

COMPOSITION

OF

RESINS

BASED

ON

MGE

AND

DGE

Fractional composition (%) of sample : 5 according to I 4 i! fractionation I :1 analy- preparatl.ve t i tical

M

250 250 286 444 480 638 674 832 868 1026 1062 ~ 1220

EPOXY

100 100

78-2 77-6 12.7 7.1 1.7 0.6 0.2

76'2 75'8 5'2 11"0 4"0 1"9 1"0 0"6 0'3 0"1 0'1

I

91.3 i' 75.7 91.3 i 74-3 8.7 I 12.0 -' 9-5 -I 1"2 --

1"3

--

,

0.4

---

I

0.4

-_ -

-

0"2 0.1 I Traces Traces

74.1 74.7 12.4 9.7 1.3 1.4 0-4 0"5 0.2 0.1 0.1 Traces

6 62-1 61-7 18.8 13.6 2"8 2.4 0"5 0-2

* D e t e r m i n e d b y calibration a c c o r d i n g t o F i g . 3.

A similar p a t t e r n is observed for M W D p a r a m e t e r s and distribution according t o t y p e s o f f u n c t i o n a l i t y w h e n obtaining resin b y condensation of a dipotassium salt o f p - h y d r o x y b e n z o i c acid w i t h E C H at the boiling p o i n t of t h e l a t t e r (sample 3). A n increase in t h e c o n t e n t of high molecular weight fractions in this case is due t o t h e higher t e m p e r a t u r e of synthesis. T h e a d d i t i o n to t h e reaction m i x t u r e of a s o l v e n t - i s o p r o p y l alcohol - - has no m a r k e d effect o n t h e c o n t e n t o f high molecular weight fractions, however, it m a r k e d l y increases t h e c o n t e n t of monoglycidyl ester resulting in a r e d u c t i o n o f t h e n u m e r i c a l - a v e r a g e f u n c t i o n a l i t y of resin (sample 6). As shown b y this brief analysis of e x p e r i m e n t a l data, p r o d u c t s of condensation of h y d r o x y b e n z o i c acids with epiehlorohydrin are e p o x y resins with M = 260-300 a n d Mw/Mn----1 "03-1"10. I n spite of significant changes in conditions of synthesis, D G E c o n t e n t in resin does n o t exceed 78%.

Translated by E.

SE~RE

:3056

S . V . VII~TOGRA.DOVAet ~ . REFERENCES

1. M. HOPPE, Swiss P a t e n t 392896, 1965 2. U. KOTASI, Polymer Appl. 24: 96, 1975 ~3. S. G. ENTELIS, V. V. YEVREINOV and A. I. KUZAYEV (book) Uspekhi khimii i fiziki polimerov (Progress in Polymer Chemistry a n d Physics). Izd. " i h i m i y a " , 1973 4. A. I. KUZAYEV, Vysokomol. soyed. A22: No. 9, 1980 (Translated in Polymer Sci. U.S.S.R. 2 2 : 9, 1980) 5 . A. L KUZAYEV, S. D. KOLESNIKOVA and A. A. BRIKENSHTEIN, Vysokomol. soyed., A17: 1327, 1975 (Translated in Polymer Sei. U.S.S.R. 17: 6, 1524, 1975) '~}. C. F. DUKER and It. W. WELCH, US. Pat. 3859314, 1975

PolymerScience U.S.S.R. Vol. 22, Printed in Poland

~ o . 12, pp.

3036-3042, 1980

0032-3950/80/123036-07507.50/0 © 1981 Pergamon Press Ltd.

.REGROUPING OF AROMATIC HETEROCHAIN POLYMERS INTO POLYARYLENE-TYPE CARBON-CHAIN POLYMERS* S . V. VINOGRADOVA, S. ~ . SALAZKIN, G. N . MELEKttINA,

L. I. KO~_AROVA and V. V. KORSHAK Institute of Hetero-Organie Compounds, U.S.S.R. Academy of Sciences (Received 26 October 1979) I t was found possible to transform aromatic polyethers containing phenoxyphthalide fragments into polyarylenes with free hydroxyl groups. This regrouping takes place as a result of purely heat effects at 200-300 ° and in the presence of a catalyst at lower temperatures (25-100°). I t was shown using model systems t h a t the phenoxyphthalide structure is very labile during regrouping, compared with the isomeric form of normal ester.

WE have recently described [1] new aromatic polyesters obtained from dicarboxylic acid dichlorides capable of sustaining cyclo-chain isomerism. It was shown that according to conditions of synthesis, two types of polymer may be formed (I and II) 0

~, F-%

/J-~

_,d--~_n-

!'l

•

0

IL 0 I

* Vysokomol. soyed. A22: No. 12, 2768-2773, 1980.

II